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Discussion Starter #1
I have never had a bad air fill, up until possibly now.

Just got my twinset back from a service and O2 clean, with a fill of air. Did my dives on that air no problem. Had my tanks filled again, but had to use a different dive shop as my normal one was on holiday. During my next dive (yesterday) I felt as if there was a very slight taste on the back of my tongue and roof of my mouth at times through the dive. I could not be sure what the taste was, it was just different and I felt I could only taste something when I thought about it. I hadn't eaten or drunk anything different than normal. For the rest of the day and evening I had a slight metalic type taste in my mouth. Just tried some breaths from the tank again and I can't be sure, but there does seem to be a slight taste of something but I can't pin it down (it is definately not an oily smell nor an exhaust type taste).

Question, how do I know if I have had a bad fill? If I can confirm a bad fill I will want to get a new O2 clean from the dive shop responsible and will not be getting fills there again.

Thanks
 

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All we wanted was a home... Manics
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Sometimes there is a slightly plastic smell when the filters have been changed.

A bad fill will either have oil in it (smoky yacky taste)
or will have co2/ co in it (major headache after diving it)

Not sure where a metallic taste would come from but someone will be along with a theory

If in doubt - empty them and refill - no point in taking risks
 

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It sounds as if you already answered your own question. If air smells off and you have an after taste it isn't good to be diving with. I have had bad air from a local shop, I had a persistent cough for months until I actually took a deep sniff of my cylinder one day and almost upchucked.

Empty the cylinder, purge it and have someone else fill it. There has been some research on compressor contaminants in breathing air and CO is just one of them. There are some real nasties released from hot compressors.

I can PM anyone a paper on compressor contaminants in breathing air compressors or you can download it http://archive.rubicon-foundation.o...9/7964/DHM_V38N3_breathing_gas.pdf?sequence=1

Dale
 

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As the shop should have a certificate indicating on when the air was last tested. Did you see this at the shop? If you are worried about the quality of the air it should be reported to your local environmental health officer then your air in the cylinder may be used for analysis. As the air may also cause problems to other divers as well. If the shop does not realise there is a problem they also need to be advised.
 

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Hi Kingfisher
There are a few ways to check, the simplest being take it to a test centre and ask them to test the air quality.(this will cost money)
you could take it back to the shop that filled it and ask their opinion (any air filling stations wont want a reputation for bad air)
another slightly more convoluted way is to pass the contents of the cylinder back through a personal filter (this will require some nice person with the right kit) and then breathe it to see if the taste has gone.
Do check when the shop had its last air test (although in reality this tells you very little, just that at that time the air was good)
Lastly check that your reg has not been contaminated by something. (chilli paste?)

Cheers
good luck

Hazel
 

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Metallic taste can allegedly come from diving using a high PPO2.

I had this once on the deeper parts of a dive (open circuit), it disappeared every time I ascended. It came back again when I switched to a rich mix for deco. I had no idea what was happening at the time :eek:mg:

On the surface all the gas tasted fine.
I've had that as well taking air too deep. Two things I really remember were the metallic taste and the sound of church bells.
 

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Discussion Starter #8
Thanks for the advice guys.

I think I will go back to the dive shop and have a chat with them and see when their air was last tested.

Just to clarify, the dive was only a shallow dive (12m) as I was practicing shut downs. And I know the reg had no contamination on it from the previous dive a week earlier.

Thanks anyway.

Kingfisher
 

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All we wanted was a home... Manics
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I've had that as well taking air too deep. Two things I really remember were the metallic taste and the sound of church bells.
church bells - spooky. Was it a premonition of your own funeral :D Just mother nature reminding you that the results of gas theory are unavoidable.
 

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Bear in mind if the tanks have been contaminated they will need to be recleaned, if the shop that did the fill has contaminated them they 'should' offer to have them cleaned.

Do not let them empty the air from the tanks until the source of the contamination has been established, if they do then all your possible evidence is gone.

Go back, leave the tanks in the car and express your concerns that their air quality may have been compromised, if they get arsey walk out. It is at this point you hand it over the the local council.
 

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All compressors rely on filters to remove oil and other contaminants from the air during compression. These are replaced at stated intervals usually time based but if a compressor sees heavier than usual use then the filters may need earlier changing. Any reputable filling station will be concerned about this possibility and it is possible they may have identified the problem by now and fixed it. Talk to them reasonably without allowing them access to your tanks at first, you may get a hansome apology and a O2 clean, if not you or local HSE or council will need to have the air analysed.
Tim Digger
 

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All compressors rely on filters to remove oil and other contaminants from the air during compression. These are replaced at stated intervals usually time based but if a compressor sees heavier than usual use then the filters may need earlier changing. Any reputable filling station will be concerned about this possibility and it is possible they may have identified the problem by now and fixed it. Talk to them reasonably without allowing them access to your tanks at first, you may get a hansome apology and a O2 clean, if not you or local HSE or council will need to have the air analysed.
Tim Digger
Alternatively they may have a fault of which they are totally unaware - give them a chance to put it right
 

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All compressors rely on filters to remove oil and other contaminants from the air during compression. These are replaced at stated intervals usually time based but if a compressor sees heavier than usual use then the filters may need earlier changing. Any reputable filling station will be concerned about this possibility and it is possible they may have identified the problem by now and fixed it. Talk to them reasonably without allowing them access to your tanks at first, you may get a hansome apology and a O2 clean, if not you or local HSE or council will need to have the air analysed.
Tim Digger
Isn't the "time based" determined by the number of hours run on the compressor, rather than "every 3 months"?
 

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Isn't the "time based" determined by the number of hours run on the compressor, rather than "every 3 months"?
It depends on the circumstances. When I joined the Lady Jenny V in 1992 as the dive guide, I asked when the compressor filters were last changed.
The reply I got was, "Filters? What filters?"
 

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Not a lot you can do here, but an old cheap first trick is to jam a white rag or handkerchief over the pillar valve hole and carefully blow a minutes worth of air over it. Then check the 3mm orifice area for discolouration or particulate contamination. it will be very slight difference, don't expect a black dot.

You may also be better to wipe over the pillar valve first and clean it before jamming the white rag over it.

From the second shops point of view if you asked and got an air fill, in all probability it will be within BS 12021 and this allows .5mg of oil per cubic meter. Your twin set contains about four cubic metres of Air. So 2mg of oil inside your cylinders is within the breathing air standards of BS 12021

Also check the face of your regulator first stage sintered disc for discolouration if you had decided to continue to dive despite a gas taste then it could be argued that it wasn't that much of a problem, and the sintered disc would have seen a greater flow. So better chance to see something.

On the two occasions I have been "the responsible" party in a suspect fill, on both occasions I removed completely the filter from the compressor and then filled a aluminium 7 ltr test cylinder with raw air unfiltered air without any form of chemical filtration.

I then fitted a regulator and on one occasion I asked the client to taste the gas, on the second occasion I offered them to try the cylinder out at Stoney Cove

Then again we supply Air for nitrox to BS EN 8478

and after breathing a sample of 8478 Air without any filtration perfectly happily, the customer looked elsewhere for the culprit.

With or without the chemical filters.

You on the other hand in all probability got what you paid for.

http://www.raf.mod.uk/rafsubaqua/rafcms/mediafiles/B88E2D9C_5056_A30A_09630860A5820ABD.pdf

Iain Middlebrook
 

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Discussion Starter #17
It is now Thursday (alright Fri morning) and I dived last Friday, phoned the dive shop Monday and was told they were glad of my call, had filled lots of cylinders for dives over the week-end and would make contact with some of the divers to see if they noticed anything. Also mentioned how frequently they change the filters (every 250hrs, the compressor was serviced fully 6 weeks ago and had an air test 4 weeks ago). They would call me back and let me know the outcome (oh and I am waiting the price of reg sevicing from them anyway so am expecting a call on 2 counts. Very good I am thinking.........................................................its now 4 full days and nothing. Not good.

I have vented the air into a clean hankie and there was no sign of any contaminationfrom the "dubious" cylinders, but a very distinctive odour in my garage which I can't describe.

Did the same check first of all with a different tank filled elsewhere - also no contamination on the hankie, but significantly, there was no odour from this tank, despite venting it for longer (expecting it to be clean which it was).

Will be calling the shop to see what feedback they got. Not good responsiveness if nothing else.

Watch this space
 

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Hopefully you haven't blown all you gas and there is still some left for analysis.

If so your next step would be to contact your local trading standards to do a free air sample test.

Ask them to (or better yet contact yourself first) Dorset trading standards as they have the test equipment and see what they say.
Contact details are below:

Divers clean air scheme - dorsetforyou.com

There test equipment is OK but not spectrographic analysis, for that you need
another sample to really get to the bottom of this.

Again the fact you dived on the gas and to no ill effect does not put it priority one.

There are three main reasons for a dirty smell from an air sample.

But first off my comment would be about this 'they change there filters every 250 hours" 250? are you sure it's not every 25 hours?

Here's what's going on and how it all works:

In the 250 or 25 hours of use the filter contains all that accumulated crude and oil crap sitting inside the filter tower.
It doesn't go anywhere but sits inside waiting.

The chemicals within either adsorb or absorb this rubbish while the emulsified fatty oil and water condensate builds up around the filter cartridge shell.

250 or 25 hours of this stuff is basically just still sitting stagnating in a sealed can.

Until something sets if off unexpectedly such as a blocked condensate drain, or drain timer or a slug of condensate is all it needs to set it all off.

And all that cumulated crap is flushed out or to use the technical term its all desorbed out again into some poor sods cylinder.

After "purging" out all this crap into a single cylinder, YOURS
the next chap in the line gets an OK if damp fill and the shop get to boast with pride that no other customers complained that week-end only you.

Because All the accumulated 250 or 25 hours worth of rubbish was dumped out into a single cylinder…………YOURS.

None of the dive shops other customers will have had a problem, making you look like an idiot for complaining and then your faced with the
insinuation in some way it's your fault. so your cost to rectify.

I see this time after time. It's all in the ignorance, lies and bullshit propagated down to keep you ignorant of facts that with oily air compressors.

FILTERS BY THERE VERY NATURE FAIL

Now the smell more likely is either the old stagnant condensate, or old oil.

If it's an acrid or sharp acid like smell/taste it can be burnt oil or a combustion by product. If that you would have canned the dive.

For cause you need to know or have a photo of the compressor and filter and know if oxygen was used at all as sometimes the
combustion of materials in high oxygen concentrations as little as 30% have been known to burn off some pretty nasty smelly gases.

At some point you need to name the dive shop in question and get the make and model of the compressor and the filter system.

The age of the plant is also sometimes useful.

Not for the first time you find 20 year old compressor built for BS 4001 doing nitrox fills under the double filter nonsense.

The sad thing here is in most cases, you the customer get to pay for the rectification and cleaning bill for your stuff.

While another 250 or 25 hours ticks by until the next unsuspecting customer comes by. Iain Middlebrook
 

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I once did a trip in Egypt where about 1/4 of the cylinders gave the air a sweet slightly rancid smell. The smell seemed to be consistent with certain cylinders, no problems diving them though, so not the compressor I guess in that case, although not to say that's not the original cause.

Re the taste of high ppO2, O2 is quite sweet, if you ever calibrate a unit with the DSV right under your nose you can really smell it. Not like those cylinders though.
 
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